A module for children's building blocks made of injection moulded thermoplastic rubber

Abstract: This invention concerns a module for children's building blocks made of injection moulded thermoplastic rubber having a soft and flexible structure.

Description: This invention concerns a children's building block made of injection moulded thermoplastic rubber. The purpose of this invention is the production of building blocks for children under the age of three. Children under the age of three can in fact not play with the building blocks currently available on the market since they are potentially dangerous for such small children who are not yet aware of certain dangers and not yet walking properly. Conventional games of this kind are generally made of very rigid polypropylene blocks: each block being open at the bottom and hollow internally with circular raised elements on the top surface. These building blocks can be press fitted on top of one another, male against female: the elements on the top surface of a block being the male elements which press fit into the bottom cavity (being the female element) of the overlying block. The reason that these conventional building blocks are not suited to smaller children lies in the very structure of the blocks themselves. In view of their rigidity, these blocks are potentially dangerous for children who might fall on them while playing and hurt themselves against the surface of the block or the sharp corners of the blocks. Moreover, on account of the fact that these blocks are very rigid, they press fit together very firmly thereby making it very difficult for small children to pull them apart. These problems led to the idea of designing building blocks having a very similar structure to conventional blocks, but which can be used safely by smaller children. In particular, the inventive idea concerns the realization of a game consisting of soft, elastic elements; it is obvious that modules of this kind would in no way be dangerous for small children since if the same fall against the modules accidently they would obviously bend, gradually absorbing the blow and then return to their original shape. Moreover, thanks to the elasticity of the modules, the male - female coupling requires very little strength enabling even small children to pull them apart very easily. The invention is set out in claim 1. Although the inventive idea is substantially straightforward, the building blocks according to the invention are by no means simple to produce since it was necessary to resolve the crucial problem of selecting the right material and manufacturing technique which would ensure the best structural solution. Even if theoretically many materials seem to be suited for producing soft and elastic elements, in practice the majority of these materials were found to be unsuitable for the required structural solution. Polypropylene, for example, would be totally ill-suited in this case, regardless of whether this were used during moulding or blowing. An attempt to mould polypropylene for this purpose would result in rigid elements like those currently available on the market, with sharp surface burring which would be dangerous for children; blowing the polypropylene, which is a procedure often used for manufacturing other types of soft toys, is just as unsuitable. It is in fact common knowledge that said blowing procedure can be used only for closed forms (such as dolls, animals, balls) but not for hollow forms, as in the case of building blocks; moreover blown polypropylene is subject to irregular and significant shrinkage when it hardens. This irregular shrinkage would create problems in manufacturing the building blocks in question because of the risk of producing blocks in different sizes (even if in the order of just a few millimetres) which would be impossible to couple together. Indian rubber, in which, theoretically, it is possible to manufacture soft building blocks, would be just as impractical in view of the high costs of both the raw material and the production process. PVC is just as unsuitable for manufacturing the element according to the invention for two fundamental reasons; first and foremost because this material is suspected of being toxic to persons, but above all because PVC is also subject to irregular and virtually uncontrollable shrinkage when it hardens; in other words, with this material it would again be impossible to manufacture blocks in identical sizes, this being essential for blocks which are to be coupled together. The same problem would also occur in the case of vulcanized or micro-porous rubber, both of which are consequently unsuited to this purpose. The best construction solution proved in fact to be that of producing the building blocks according to the invention in thermoplastic rubber injected into steel or aluminium moulds. This manufacturing technique not only ensures good structural results (in that the blocks are sufficiently soft and elastic) but is also inexpensive enough to make it particularly convenient for the production of large scale quantities of the items in question. The preferred embodiment of the construction solution moreover makes it possible to produce the blocks at an industrial level in identical and precise sizes in that thermoplastic rubber is subject to constant shrinkage, which can be estimated with a good degree of accuracy, when it hardens in the mould. This consequently ensures that the moulded blocks can be coupled easily and precisely, male against female, with other blocks, be these blocks manufactured during the same production run or in different production runs. Finally, it should be reiterated that the block module according to the invention should also have a conventional cavity at the bottom as well as a series of circular elements projecting from its upper horizontal surface; moreover said modules may be produced in different sizes so as to allow children to build many different shapes and objects.

Claims: Children's building block consisting of a hollow structure with open bottom and a series of projecting circular elements on the upper surface, characterized in that the block is made of injection moulded thermoplastic rubber and in that its structure is soft and flexible.

Inventors: PEPA SAURO, PEPA, SAURO
Applicants: MARPLAY SRL, MARPLAY S.R.L.
Application year: 1994
Main classification: A63H33
IPC codes: A63H33